NAPER, Nebraska — Standing on the banks of the Keya Paha River where it cuts through his farm, Bob Allpress points across a flat expanse of sand to where a critical shut-off valve is supposed to rise from the Keystone XL pipeline once it's buried in his land. The Keya Paha flooded several weeks ago, and when it did, the rush of newly melted water drove debris, sand and huge chunks of ice deep inland, mowing down trees and depositing a long wall of ice 6 feet high and 30 feet wide across Allpress's property.

"It would've taken out their shut-off valve," Allpress said of the river flooding. "Right where they propose to put it at. And it wouldn't have been a good thing."

If the Trump administration and the state of Nebraska have their way, the Keystone XL oil pipeline will be built, and about a mile of it will slice through Allpress's 900-acre farm, where he and his brothers raise corn, alfalfa and cattle.

Bob Allpress points to where the Keystone XL pipeline is slated to cut through his land. Flooding this spring swept across the area where a shut-off valve for the oil pipeline is expected to go. Credit: Anna Belle Peevey

A former oil-field worker and avowed Republican, Allpress, like many local landowners, has long opposed the pipeline, which would pass through floodplains and erosion-prone land. Now, the catastrophic spring flooding that devastated parts of Nebraska has swept that threat into the spotlight, as the Trump administration works to fast-track construction by overriding environmental reviews.

Opponents of Keystone XL have successfully stymied the project's completion for years with legal challenges over threats to regional drinking-water aquifers, streams, wildlife habitat and the global climate. The pipeline would carry tar sands crude 1,200 miles from Hardisty, Canada, to Steele City, Nebraska, where it would connect to other pipelines to Gulf Coast refineries.

After extensive environmental reviews, the Obama administration refused to grant the project a presidential permit, finding that it was not in the national interest. President Trump reversed that decision, but environmentalists claimed the project needed a new environmental impact statement before it could proceed, in part because of a new route through Nebraska, and so far the courts have agreed.

Without adequate environmental review, grave risks such as flooding and erosion "haven't been analyzed and the pipeline is going to go forward without agencies fully understanding risks and threats to the project," said Doug Hayes, a lawyer for the Sierra Club, which is a plaintiff in the suits.

The threat to pipelines from erosion prompted the Pipeline and Hazardous Materials Safety Administration, the federal regulator responsible for the safe operation of the country's energy pipelines, to issue an advisory two weeks ago to pipeline owners. It urged them to institute safeguards after a recent spate of accidents from soil shifting around pipelines. In the last decade, fast currents and high floodwaters exposed two pipelines in the Yellowstone River in Montana that both ruptured, leaking a total of about 93,000 gallons of oil.

The Nebraska flooding this spring destroyed a dam, washed away bridges and roads and drastically changed the contours of waterways. Critics of the Keystone XL project see a risky convergence ahead if the pipeline gets built.

The 2018 National Climate Assessment warned that Nebraska could face more of the intense rainfall and wet spring weather that overwhelmed the state this year. Nebraska scientists who worked on the climate assessment noted that climate change would put the state's fossil fuel infrastructure at risk. In a finding echoed for at least five years in authoritative government reports, the latest climate assessment said pipelines in the northern Great Plains including Nebraska "are vulnerable to damage or disruption from increasing heavy precipitation events and associated flooding and erosion."

The state Public Service Commission, which approved the pipeline route, declined to comment about the possible impact of flooding, citing litigation. But Commissioner Crystal Rhoades wrote: "I continue to be concerned about the stability of the soils. I suspect we will see an increase in flooding events as climate change continues to exacerbate weather. I think the state would be doing a disservice to our constituents if we didn't continue to monitor the impacts of climate change on our state and its infrastructure, including the KXL."

Rhoades is one of two commissioners who dissented when the commission approved the current Nebraska route for Keystone XL.

The pipeline's builder, TC Energy, formerly called TransCanada, did not reply to requests for comment about flooding and erosion risks. The company said earlier this month that delays related to the multiple lawsuits have caused it to miss the 2019 construction season.

Nebraska regulators have been alerted about the threat erosion poses on the routes it considered for Keystone XL. TC Energy, for instance, preferred a different route than the one approved because it said the PSC route had a higher prevalence of erodible soil. A contractor for the PSC delivered a report in 2017 showing that all the routes the state reviewed had considerable stretches of highly erodible soil, including in Keya Paha County, where Allpress lives.

The Problem of Shifting, Slide-Prone Soil

If the Keystone XL pipeline gets built on Allpress's land, it would run underground from an abandoned pioneer schoolhouse on a grassy hilltop, down a slope and across fields before passing under the Keya Paha River into a neighbor's land. When he learned of the route from TC Energy, Allpress told them they picked the wrong place for a pipeline.

The hills here are all slide-prone, he said, because the soil and clay that sit on a shale formation shift considerably when enough water gets into the earth. Within a mile of his property, six big hills have slid up to an acre in his lifetime, said Allpress, who is a member of Bold Nebraska, a statewide grassroots organization that opposes Keystone XL.

"Once you break this soil and provide a water channel to the depths, you have the potential for any type of blowout, because they're going to screw up the composition once they trench the pipeline in," Allpress said. "Even if they take measures coming down these hills, it's going to cause erosion and blowouts of the pipeline."

Intense rainfall can erode soil that is already unstable. In the Pipeline and Hazardous Materials Safety Administration advisory, three of the seven recent ruptures the regulator cited occurred because of heavy flooding or "excessive moisture" in the soil.

Pipeline companies bury their pipelines at prescribed depths, based on their permits. But there is no requirement that they maintain over time those original depths or amount of soil cover, said Rebecca Craven, program director at the Pipeline Safety Trust, a watchdog group based in Bellingham, Washington.

"So what can happen is that as rivers flood and scour their beds, or as stream channels migrate, a lot of sediment can get moved," Craven wrote in an email, "and pipelines can be exposed alongside rivers, or the forces of the water (or ice) can cause a failure of the pipeline."

Midwest Flooding Put a Spotlight on Pipeline Risk

The risk to underwater pipelines from rivers scouring their beds has been known for years, including the threat it could pose to Keystone XL. But the recent Nebraska flooding brought the risks to the fore.

A year after an ExxonMobil pipeline in the Yellowstone River was ripped open by scouring in 2011, the Wall Street Journal reported that pipeline oversight was so lax that dozens of other pipelines nationwide faced similar risks. The 2014 Final Supplemental Environmental Impact Statement (SEIS) for Keystone XL discussed the threat of river scouring, noting that "all states affected by the proposed Project are prone to ice jams on their major rivers, which often cause substantial backwatering and lateral scour."

Even under the Trump administration a new draft SEIS issued in 2018 said, "Flood events may increase the potential for a pipeline release because of erosion and channel migration. Erosion may arise from seasonal flood events or increased stream velocities, which in turn undermine support soils, increase lateral water force and increase the impact from waterborne debris. If a pipeline release does occur during a flood, pipeline components (e.g., valves, regulators, relief sets, pressure sensors, etc.) may become submerged and either inoperable or inaccessible."

The State Department declined to answer specific questions about new risks uncovered by the Nebraska flooding, saying only that the Keystone XL project is still under environmental review.

TC Energy commissioned a study of a Keystone XL crossing at the Missouri River in Montana which recommended using horizontal directional drilling to bury the pipeline up to 54 feet below the riverbed. The company has also proposed using directional drilling to place Keystone XL at least 25 feet below the river bottom when crossing major Nebraska rivers, such as the Platte and Elkhorn, and environmentally sensitive creeks, too.

'It's Gonna Wash Out That Pipeline'

At all the remaining dozens of Nebraska waterways, including the Keya Paha River, Keystone XL will be installed using the conventional "open-cut" method, including at the north branch of Eagle Creek that runs across Byron "Stix" Steskal's property in Holt County. An open cut is a trench several feet deep that the pipe is placed into. Keystone XL itself is 3 feet in diameter.

After the damage Steskal saw from the spring flooding, he worries that Keystone XL, once it stretches 6,000 feet through his land, won't be buried deep enough to prevent erosion and damage from the water.

"I'm sure that with all the smaller creeks that the proposed TransCanada pipeline crosses, that with an open cut, each one of those smaller streams would have showed that the pipe was bare, and then you have also trees and debris along with ice coming down there," he said. "What's going to happen is, it's gonna wash out that pipeline that's underneath the Eagle Creek."